A rectangle is a four-sided polygon, or quadrilateral, with opposite sides equal in length and every angle measuring \(90 ^\circ\) . It is a special type of parallelogram and one of the most fundamental shapes in geometry, widely used in mathematics, design, and everyday life.
The perimeter is the total distance around the rectangle, calculated as:
\[ P = (a + b) \times 2 \]
where:
The area is the amount of space enclosed by the rectangle:
\[ A = a \times b \]
where:
The diagonal is the line segment connecting opposite corners of the rectangle. Using the Pythagorean theorem:
\[ d = \sqrt{a^2 + b^2} \]
where: